Recently, portable or notebook computers have become a popular alternative to traditional desktop computers in terms of their movability, simplicity, and various functions. Further, various expansion devices have been developed for enabling the notebook computers to extend battery life as well as perform a multimedia function. This is to overcome inherent functional limitations of the notebook computer due to its reduced size and limited battery life. Those expansion devices, for example, external speakers, external CD-ROM drives, external batteries, etc. are often incorporated into an apparatus, called a docking station, that is arranged for a specific notebook computer.
In an earlier portable computer arrangement, a notebook computer having small internal speakers is coupled to a docking station through a docking connector. The docking station has relatively high power speakers in order to perform multimedia presentations with a high quality sound reproduction.
In such an earlier portable computer arrangement, the notebook computer includes a sound source and an audio chip and an audio amplifier and a speaker while the docking station includes an additional audio chip, an audio amplifier, and another speaker. The docking connector is disposed between the output of the sound source of the host computer and the input of the docking station audio chip. Exemplars of such designs during recent years include those found in U.S. Pat. No. 5,671,366 to Niwa et al., entitled Operating System Optimization To Permit Use Of A First Unit With A Second Unit To Extend The Functionality Of The First, U.S. Pat. No. 5,526,493 to Shu, entitled Docking Detection And Suspend Circuit For Portable Computer/Expansion Chassis Docking System, U.S. Pat. No. 5,598,537 to Swanstrom et al., entitled Apparatus And Method For Driving A Bus To A Docking Safe State In A Dockable Computer System Including A Docking Station And A Portable Computer, U.S. Pat. No. 5,598,539 to Gephardt et al., entitled Apparatus And Method For Achieving Hot Docking Capabilities For A Dockable Computer System, U.S. Pat. No. 5,632,020 to Gephardt et al., entitled System For Docking A Portable Computer To A Host Computer Without Suspending Processor Operation By A Docking Agent Driving The Bus Inactive During Docking, and U.S. Pat. No. 5,630,175 to Gajewski et al., entitled Surround Sound System For General Purpose Computer Using Dual Sound Cards.
Digital sound data from the sound source of the computer is supplied to the host audio chip when the computer is separated from the docking station. The audio chip converts input digital sound data into analog audio signals which are supplied to the audio amplifier. The amplified audio output is supplied to the small internal speaker. The audio output of the audio amplifier of the computer is set to a low level so that it can be matched to the small low power internal speaker.
On the other hand, when the notebook computer is coupled to the docking station, the computer system controls the input of the host audio chip to disable the operation of the audio chip and the digital sound data of the sound source is supplied to the additional audio chip provided in the docking station through the docking connector. Converted analog audio signals are supplied to the station audio amplifier and the thus amplified audio output is supplied to the high power speaker of the docking station. Since the audio chips are duplicated unnecessarily in both the computer and the docking station, it would be desirable for the audio chip in the docking station to be eliminated such that the audio chip in the portable computer is used when the portable computer is coupled to the docking station to enhance sound reproduction.